In general, in order for a series of continuous operations comprising, for example, the operation for drawing out the photographic film from a master roll, the operation for measuring the length of the film, the operation for cutting the film to a specified length and the operation for stopping the leading end of the film at the exact position for being wrapped around a spool to be speeded, it is desirable for each of the devices for performing the operations to be provided on each of plural nests comprising the devices for performing the operations. The nest being arranged equidistantly on a rotary turret so that all the operations ranging from the measuring to taking up can be completed during each rotation of the turret. More specifically, by being arranged in this fashion, the film scrolls in the quantity corresponding to the number of the nests can be manufactured efficiently during each rotation of the turret.
On each of the nests arranged on the turret, in order for the leading end of the film formed after undergoing the measuring and cutting processes to be stopped exactly for being engaged with the spool held by a spool chucking device, it is necessary for the slit of the spool to be positioned so as to exactly match the leading end of the film and then for the operation for feeding the leading end of the film to the spool to be performed consecutively.
In the conventional spool positioning mechanisms the spool holding unit is linked to a shaft which receives the rotary force from a torque motor or a hysteresis clutch which produces the slip and a stopper slidably in contact with the spool so that the spool, can be positioned by causing a rib provided round the external circumference of the spool to come into contact with the stopper as the spool rotates. However, the rib bounces instantaneously when the rib comes into contact with the stopper following the increase in the speed of revolution through the increase in the torque of the torque motor and that in the transmission torque of the hysteresis clutch. That is, the spool is forced to rotate reversely against the turning force of the torque motor before the spool recovers its rotation in normal direction to come into contact again with the stopper. Such bouncing of the rib also occurs at the time of its re-contact with the spool to cause the spool to turn in reverse and normal directions alternately, though such bouncing will gradually attenuate to complete the positioning of the spool after a considerable length of time. Besides, in the conventional positioning mechanism, it is difficult for the timing of the film leading end feed to be adjusted to the timing of the spool positioning, as the poor adjustment of such timing can cause jamming of the film.